This invention relates generally to engines and more particularly, to methods and apparatus for sensing pressure in combustion cylinders of reciprocating engines and combustion chambers of gas turbine engines.
Pressure within combustion cylinders and chambers of various types of engines impacts operation of such engines. For example, gas turbine engines typically include a compressor section, a combustor section, and at least one turbine section. The compressor compresses air, which is mixed with fuel and channeled to the combustor. The mixture is then ignited to generate hot combustion gases. The combustion gases are channeled to the turbine which extracts energy from the combustion gases for powering the compressor, as well as producing useful work to power a load such as an electrical generator or to propel an aircraft in flight.
Gas turbine engines operate in many different operating conditions, and combustor performance facilitates engine operation over a wide range of engine operating conditions. Controlling combustor performance facilitates improving overall gas turbine engine operations.
The environment within combustion cylinders and combustion chambers is harsh, which limits the types of pressure sensors that can be used. For example, temperature within the cylinders of internal combustion engines can reach over 1000° F. Known pressure sensors that utilize piezo-electric and piezo-resistive elements have limited life within such environment or require cooling, which increases the material and assembly costs for such engines.
Fiber optic based systems have been used in connection with sensing pressure in harsh environments. Producing reliable and robust sensors based on fiber optic materials, however, is challenging and has impacted widespread use of such sensors.